Rapid and sensitive determination of lactoferrin in milk powder by boronate affinity amplified dynamic light scattering immunosensor

Lactoferrin (Lf) is a bioactive multifunctional glycoprotein that belongs to the transferrin family. As an important nutritional fortifier, Lf is one of the star nutrients in milk powder. Thus, the rapid and accurate quantitative detection of Lf content in milk powder is crucial to the evaluation of its quality. However, most reported immunoassay methods for Lf quantitation suffer from cumbersome sample pretreatment or lengthy testing time and do not meet the requirements for rapid Lf detection in milk powder. Herein, we report a novel method combining dynamic light scattering (DLS) immunosensing and boronate affinity recognition for the rapid and sensitive detection of Lf. Owing to the selective binding between a boronate ligand and the cis diol, the developed DLS immunosensor quantitatively detected Lf with saving one antibody, greatly reducing the need for matching antibodies, which are needed in traditional sandwich immunoassay for biomolecular detection. In addition, the DLS immunosensor exhibited high selectivity and sensitivity to Lf, with a detection limit of 1 ng/mL within ∼15 min through coupling with magnetic nanoparticle-assisted immunomagnetic separation and DLS signal transduction.